1. Field of the Invention
The present invention relates to a base attachment structure applied to a cutting tool, such as a jig saw, and more specifically to a base attachment structure disposed below a cutting tool to come into contact with a work and guide movements of the cutting tool.
2. Description of the Related Art
An example of such base attachment structure is disclosed in JAPANESE PATENT LAYING-OPEN GAZETTE No. 5-209475 filed by the inventors of the present invention. In this prior art structure shown in FIG. 5, a jig saw 120 is joined and connected with a base 121, which is disposed below the main body of the dig saw 120 and has a slide aperture 122, by means of a nut 124 and a bolt 123 piercing into the slide aperture 122 to the main body of the jig saw 120. Whereas a control lever 125 is fixed to the nut 124 disposed on a side close to the main body off the jig saw 120, the head of the boll 123 on a side off the base 121 is locked by means of a locking member 126 in order to prevent rotation of the bolt 123. The base 121 is easily locked and unlocked through rotating operations of the control lever 125. This structure allows the base 121 to be fixed by an appropriate clamping force.
The prior art structure using the control lever 125 and the bolt 123 increases the pitch of the threads on the bolt 123 to decrease the stroke of rotation of the control lever 125 for good control ability. This may, however, lead to a drawback of easily loosening the clamped bolt 123. The smaller pitch of the threads, on the contrary, effectively prevents the bolt 123 from being easily loosened, but increases the stroke of rotation of the control lever 125, thereby worsening the control ability. Another problem arising is that the body of the jig saw 120 limits the rotation of the control lever 125.